You haven't said what this plant is, but if its a pear tree, then its suffering a bad case of Pear Rust, see the RHS link below

https://www.rhs.org.uk/advice/profile?PID=236

absolutely fascinating! The rust needs both of the plants to complete its life cycle....ins't that incredible. Pear and Juniper....who'd have thought. The world of plants is endlessly incredible!